The present invention relates generally to the field of fuel processors and in particular to a new and useful auto-thermal reformer for reforming hydrocarbon-based fuels to make hydrogen rich gas.
Fuel cell systems that generate electricity from hydrogen rich gas to provide stationary, decentralized energy supplies, or for use as an energy source for electric vehicles, are the subject of research activity throughout the world. At present, economic and practical aspects dictate that only universally available and generally accepted fuels can be considered for hydrogen rich gas generation. Natural gas is particularly attractive for stationary applications, whereas use of liquid hydrocarbon fuels is more likely in the mobile sector.
Reforming is a term of art used to describe the process of generating hydrogen rich gas for use in fuel cells. Reformers that generate hydrogen rich gas on an industrial scale have been known for decades; however, these industrial scale reformers cannot be efficiently scaled down for decentralized and/or mobile applications in the range of several tens or hundreds of kilowatts (kW). Steam-reforming and Auto-thermal reforming (ATR) are specific methods of reforming.
In ATR, fuel is partially reacted by adding air to the fuel and steam mixture in the reformer to heat it to the appropriate reaction temperatures. ATR is advantageous because it has lower steam requirements (e.g. a molar steam to carbon ratio of about 2.5 to 3.5) than steam reforming and it improves efficiency in comparison to steam-reforming. ATR relies on flameless oxidation of oxygen from the air, thereby resulting in combustion of about 20 to 33% of the fuel and a release of the heat needed to drive the ATR reforming reactions.
The unoxidized fuel endothermically reacts with steam to create a mixture of hydrogen, carbon monoxide and carbon dioxide. An ATR reformer quickly adapts to new operating conditions because of its direct coupling and dynamic ability to respond to changing loads. Furthermore, ATR does not require additional external burners (and their attendant power supplies), making the system less complex and less expensive.
It is an object of the present invention to provide an auto-thermal reformer system for converting liquid fuels into hydrogen rich gas for further possible use in a fuel cell power system.
Accordingly, an auto-thermal reformer is provided having a plurality of reformer modules housed within a pressure vessel, and including an integrated steam superheater which uses the hydrogen rich gas to beat the incoming steam mixture. The individual modules also contain catalyst beds and a heat exchanger for converting hot, atomized and vaporized liquid fuel into hydrogen rich gas.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.